OSS has experimental output support for USB audio devices, but no input.

OSS supports MIDI devices with the help of a software synthesizer such as Timidity or FluidSynth.

Install

Install ossAUR which is available in the AUR. There is also a development version of OSS available in the AUR with the oss-gitAUR package.

This will install the OSS, run the OSS install script (temporarily disabling the ALSA modules) and install the OSS kernel modules. Since ALSA is enabled by default in the boot scripts, you need to disable it so it does not conflict with OSS. You can do this by blacklisting the module:

/etc/modprobe.d/alsa_blacklist.conf

install soundcore /bin/false

After blacklisting the module, you can enable the oss daemon to start at boot.

In case you are not part of the audio group, add yourself and relogin for the changes to take effect:

# gpasswd -a $USER audio

In case OSS is not able to detect your card when starting it, run:

# ossdetect -v
# soundoff && soundon

Testing

Warning: The default volume is very loud, avoid using earphones and physically lower the volume of your speakers (if possible) before running the test.

Test OSS by running:

$ osstest

You should be able to hear music during the test process. If there is no audio, try to adjust the volume or refer to the #Troubleshooting section.

If you want to hear sounds from more than one application simultaneously, you need vmix, OSS's software mixer.

Check that vmix is enabled by running:

$ ossmix -a | grep -i vmix

You should see a line like vmix0-enable ON|OFF (currently ON). If you do not see any lines beginning with vmix, it probably means that vmix has not been attached to your sound device. To attach vmix, issue the command:

$ vmixctl attach device

where device is your sound device, e.g. /dev/oss/oss_envy240/pcm0.

To avoid having to issue this command manually in the future, you can add it to /usr/lib/oss/soundon.user, as suggested here.

If you get a "Device or resource busy" error, you need to add vmix_no_autoattach=1 to /usr/lib/oss/conf/osscore.conf and then reboot.

See which devices are detected by running:

$ ossinfo

You should be able to see your devices listed under Device Objects or Audio Devices. If the device that you want to use is not at the top of one of these sections, you have to edit /usr/lib/oss/etc/installed_drivers and place the driver for your device at the very top. It may be required to do a:

$ soundoff && soundon

If this does not work, comment all drivers listed except the ones for your device.

Volume Control Mixer

To control the volume of various devices, mixers levels will need to be set. There are two mixers:

ossmix: a command-line mixer, similar to the BSD audio mixer mixerctl.

The vmix (virtual mixer) special configurations appear at the top. These include sampling rate and mixer priority.

These are your sound card jack configurations (input and output). Every mixer control that is shown here is provided by your sound card.

Application vmix mixer controls and sound meters. If the application is not actively playing a sound it will be labeled as pcm08, pcm09... and when the application is playing the application name will be shown.

Color Definitions

For high definition (HD) audio, ossxmix will color jack configurations by their pre-defined jack colors:

Color

Type

Connector

green

front channels (stereo output)

3.5mm TRS

black

rear channels (stereo output)

3.5mm TRS

grey

side channels (stereo output)

3.5mm TRS

gold

center and subwoofer (dual output)

3.5mm TRS

blue

line level (stereo input)

3.5mm TRS

pink

microphone (mono input)

3.5mm TS

Saving Mixer Levels

Mixer levels are saved when you shut off your computer. If you want to save the mixer level immediately, execute as root:

# savemixer

savemixer can be used to write mixer levels to a file with the -f switch and restore by the -L switch.

Configuring Applications for OSS

Applications that use GStreamer

If you have problems with applications that use Gstreamer for audio, you can try removing pulseaudio and installing the gstreamer0.10-good-plugins package which is needed by oss4sink and oss4src.

Then you have to change the GStreamer settings to output the sound to OSS instead of the default ALSA with gstreamer-properties (part of the gnome-media package). After starting gstreamer-properties, you have to modify the fields as follows:

in the Default Output section: if OSS is not available as a plugin, change Plugin to Custom and Pipeline to oss4sink.

in the Default Input section: if OSS is not available, change Plugin to Custom and Pipeline to oss4src.

Note: You can also use osssrc as an alternative to oss4src if you find that it produces better sound.

Some applications (e.g. Rhythmbox, Totem) do not read the settings set by gstreamer-properties, as they rely on musicaudiosink instead of audiosink (which is modified by gstreamer-properties).

To work around this, you can set the values for audiosink with gstreamer-properties and use gconf-editor to copy the value of /system/gstreamer/0.10/default/audiosink to musicaudiosink (at the same location).

If you are using Phonon with the GStreamer backend you will need to set a environmental variable:

export PHONON_GST_AUDIOSINK=oss4sink

You can add this to your ~/.bashrc to be loaded on login.

Applications that use OpenAL

By default OpenAL uses ALSA. To change this, simply define the usage of OSS in /etc/openal/alsound.conf:

/etc/openal/alsound.conf

drivers=oss

Audacity

If Audacity starts, but it complains that it cannot open the device or simply does not play anything, then you may be using vmix which prevents Audacity from having exclusive access to your sound device. To fix this, before running Audacity, run:

$ ossmix vmix0-enable OFF

You can restore vmix after closing Audacity with:

$ ossmix vmix0-enable ON

Gajim

By default, Gajim uses aplay -q to play a sound. For OSS you can change it to the equivalent ossplay -qq by going to Edit > Preferences > Advanced, opening the Advanced Configuration Editor and modifying the soundplayer variable accordingly.

MOC

To use MOC with OSS v4.1 you must change OSSMixerDevice to /dev/ossmix in your configuration file (located in ~/.moc). For issues with the interface try changing the OSSMixerChannel by pressing w in mocp (to change to the sofware mixer).

MPD

MPD is configured through /etc/mpd.conf or ~/.mpdconf. Check both of these files, looking for something that looks like:

/etc/mpd.conf

...
audio_output {
type "alsa"
name "Some Device Name"
}
...

If you find an uncommented (the lines do not begin with #'s) ALSA configuration like the one above, comment all of it out, or delete it, and add the following:

/etc/mpd.conf

...
audio_output {
type "oss"
name "My OSS Device"
}
...

Further configuration might not be necessary for all users. However, if you experience issues (in that MPD does not work properly after it has been restarted), or if you like having specific (i.e. more user-configured, less auto-configured) configuration files, the audio output for OSS can be more specifically configured as follows:

First, run:

$ ossinfo | grep /dev/dsp

Look for the line that says something similar to /dev/dsp -> /dev/oss/<SOME_CARD_IDENTIFIER>/pcm0. Take note of what your <SOME_CARD_IDENTIFIER> is, and add these lines to your OSS audio_output in your MPD configuration file:

Skype

The skype package only includes support for ALSA, since OSS support was dropped in the recent versions. To get an OSS-capable Skype, install the skype-ossAUR package from the AUR.

Or use pulseaudio with module-oss: Edit /etc/pulse/default.pa, comment out the line that starts with load-module module-udev-detect and add load-module module-oss device="/dev/dsp" sink_name=output source_name=input mmap==0.

Other applications

Search for OSS specific packages by using pacman -Ss -- -oss or by looking in the AUR.

Tips and tricks

Using multimedia keys with OSS

An easy way to mute/unmute and increase/decrease the volume is to use the ossvolAUR script, available in the AUR. For more information about the script see this article on the OSS wiki.

Once you installed it, type:

$ ossvol -t

to toggle mute, or:

$ ossvol -h

to see the available commands.

Note: If ossvol gives an error like Bad mixer control name(987) 'vol', you need to edit the /usr/bin/ossvol script and change the CHANNEL variable to your default channel (usually vmix0-outvol).

If you want to use multimedia keys with ossvol, see Extra Keyboard Keys and make sure they are properly configured. After that you can use, for example, Xbindkeys to bind them to the ossvol script. Add the following to your ~/.xbindkeysrc file:

and optionally change the multimedia keys with whatever shortcuts you prefer.

Changing the Sample Rate

Changing the output sample rate is not obvious at first. Sample rates can only be changed by root and vmix must be unused by any programs when a change is requested. Before you follow any of these steps, ensure you are going through a receiver/amplifier and using quality speakers and not simply computer speakers. If you are only using computer speakers, do not bother changing anything here as you will not notice a difference.

By default the sample rate is 48000hz. There are several conditions in which you may want to change this. This all depends on your usage patterns. You want the sample rate you are using to match the media you use the most. If your computer has to change the sampling rate of the media to suit the hardware it is likely, though not guaranteed, that you will have a loss in audio quality. This is most noticeable in down sampling (ie. 96000hz → 48000hz). There is an article about this issue in Stereophile which was discussed on Apple's CoreAudio API mailing list if you wish to learn more about this issue.

Sample rate of SACD high definition audio discs/downloads. It is rare that your motherboard will support this sample rate.

96000hz

Sample rate of most high definition audio downloads. If your motherboard is an AC'97 motherboard, this is likely to be your highest bitrate.

192000hz

Sample rate of BluRay, and some (very few) high definition downloads. Support for external audio receiver equipment is limited to high end audio. Not all motherboards support this. An example of a motherboard chipset that would support this includes HD Audio.

To check what your sample rate is currently set to, run:

ossmix | grep rate

You are likely to see vmix0-rate <decimal value> (currently 48000) (Read-only).

If you do not see a vmix0-rate (or vmix1-rate, etc.) being outputted, then it probably means that vmix is disabled. In that case, OSS will use the rate requested by the program which uses the device, so this section does not apply. Exception to this are Envy24 (and Envy24HT) cards that have a special setting envy24.rate which has a similar function (see the oss_envy24 manpage).

To change your sample rate:

First, make sure your card is able to use the new rate. Run ossinfo -v2 and see if the wanted rate is in the Native sample rates output.

As root, run /usr/lib/oss/scripts/killprocs.sh. Be aware, this will close any program that currently has an open sound channel.

Note: If you are using Opera you must kill operapluginwrapper before suspend. To do this add pid=$(pidof operapluginwrapper) && kill $pid before s2ram -f.

Changing the Default Sound Output

When running osstest, the first test passes for the first channel, but not for the stereo or right channel, it sounds distorted/hisses. If this is what your sound is like, then it is set to the wrong output.

cd to src/kernel/setup and edit srcconf_linux.inc, search for -Werror and remove it, otherwise OSS will not compile.

do makepkg --noextract

Now you must install the package with pacman -U. Remove OSS first if already installed.

ALSA emulation

You can instruct alsa-lib to use OSS as its audio output system. This works as a sort of ALSA emulation.

Note, however, that this method may introduce additional latency in your sound output, and that the emulation is not complete and does not work with all applications. It does not work, for example, with programs that try to detect devices using ALSA.

So, as most applications support OSS directly, use this method only as a last resort.

In the future, more complete methods may be available for emulating ALSA, such as libsalsa and cuckoo.

Instructions

Install the alsa-plugins package, available in the official repositories.

Try changing defaults. There are only few settings, and they are self explanatory

For example, the setting:

ich_jacksense = 1

in oss_ich.conf turns on jack-sense (which is responsible for recognizing plugged headphones and muting the speaker). Other settings for jack-sense can be found in hdaudio.conf where you have to change the hdaudio_jacksense variable.

Troubleshooting

Troubleshooting HD Audio devices

Understanding the problem

If you have a HD Audio sound device, it is very likely that you will have to adjust some mixer settings before your sound works.

HD Audio devices are very powerful in the sense that they can contain a lot of small circuits (called widgets) that can be adjusted by software at any time. These controls are exposed to the mixer, and they can be used, for example, to turn the earphone jack into a sound input jack instead of a sound output jack.

However, there are also bad side effects, mainly because the HD Audio standard is more flexible than it perhaps should be, and because the vendors often only care to get their official drivers working.

When using HD Audio devices, you often find disorganized mixer controls, that do not work at all by default, and you are forced to try every mixer control combination possible, until it works.

Solution

Open ossxmix and try to change every mixer control in the middle area, that contains the sound card specific controls, as explained in the OSS#Volume Control Mixer section.

You will probably want to setup a program to record/play continuously in the background (e.g. ossrecord - | ossplay - for recording or osstest -lV for playing), while changing mixer settings in ossxmix in the foreground.

Raise every volume control slider.

In each option box, try to change the selected option, trying all the possible combinations.

If you get noise, try to lower and/or mute some volume controls, until you find the source of the noise.

Editing /usr/lib/oss/conf/oss_hdaudio.conf, uncommenting and changing hdaudio_noskip=0 to a value from 0-7 can give you more jack options in ossxmix.

Note: If you modify this file, restart the oss daemon for the changes to take effect.

MMS sound cracking in Totem

If you hear various cracks or strange noises in Totem during playback, you can try using another backend such as FFmpeg. This will not fix the issue that somehow pops up in GStreamer when playing MMS streams but it will give you the option to play it with good sound quality. Playing it in MPlayer is simple:

# mplayer mmsh://yourstreamurl

Microphone playing through output channels

By default, OSS plays back the microphone through the speakers. To disable this in ossxmix find the Misc section and uncheck every input-mix-mute box.